Northern Alaska's 12 Known Dinosaurs

Twelve known dinosaur types have been found on the North Slope. All are about 68-72 million years old and are from the late Cretaceous Period.

This summary is based primarily on material from Dr. Roland A. Gangloff, UAF with additions by Dr. Robert E. King, BLM.

Hadrosaurs were large, plant-eating, duck-billed dinosaurs that walked on two legs.

Edmontosaurus (Ed-MON-toh-SORE-us) — 10 feet tall, more than 40 feet long, weighing up to three or more tons, non-crested, most common type known; found in Alaska: teeth and more than 60 percent of its bones; juveniles and young adults dominate recovered remains

Kritosaurus(KRITE-oh-SORE-us) — around 10 feet tall, up to 30 feet long, weighing about three tons, non-crested; found in Alaska: teeth

Lambeosaurid(LAMB-ee-oh-sore-id) — crested but genus uncertain; can be more than 10 feet tall, up to 50 feet long, weighing more than three tons; found in Alaska: teeth and upper jaw.

Ceratopsians(SERRA-tops-ee-ns)were large, plant-eating, horned dinosaurs that walked on four legs.

Anchiceratops (AN-ki-ser-ra-tops) — up to seven feet high, 16-20 feet long, weighing up to 4 four tons, found in Alaska: part of rear end of skull.

Hypsilophodontids were small, swift-running, plant-eating dinosaurs that walked on two legs.

Thescelosaurus(Thes-kel-oh-SORE-us) — less than five feet high, 11 feet long, 200 pounds; found in Alaska: teeth and toe bone.

Theropods were fast-running, meat-eating dinosaur of various sizes with sharp serrated teeth. They are thought to have hunted in packs or social groups. They walked on two legs. Theropods found so far are grouped into three familes:

Tyrannosaurids had massive heads and highly reduced arms.

Albertosaurus (Al-BERT-to-SORE-us) — up to 10 feet tall, 15-17 feet long, a smaller "cousin" of the famous Tyrannosaurus rex (T.rex); found in Alaska: isolated teeth and rare bones.

Tyrannosaurus (Tie-RAN-oh-SORE-us) — under 15 feet tall, 10-15 feet long, species not known; found in Alaska: a single tooth; specimen probably an earlier "cousin" of T.rex, same genus.

Troodontids had relatively large brains. Their large eyes possibly were better adapted for hunting during twilight or at high latitudes.

Dromaeosaurids were possibly the fastest, fiercest predators of any knid.

Dromaeosarus(DROH-may-oh-SORE-us) — small, lightly built, around four feet tall, six feet long, 100 pounds; a "cousin" to the scary Velociraptor made famous in the movie "Jurassic Park" -- just the size to look a 10-years-old child in the eye if standing upright! Found in Alaska: isolated teeth and a single tail vertebra.

Saurornitholestes(Sore-OR-nith-oh-LES-teez) —very similar to Dromaeosaurus, four feet tall, six feet long, 100 pounds; found in Alaska: isolated teeth and vertebra.

Pachycephalosaurids were relatively small, plant-eating dinosaurs that walked on two legs; notable for having thick domed skulls suggesting that some may have used them for head0butting, or some other ritual combat. Recent studies indictate adaption for heat dissipation or loss.

Pachycephalosaurus(PAK-ee-sef-a-loe-SORE-us) — not more than 7 feet tall, 15 feet long, 300 pounds; species not known; found in Alaska: egg-sized skull fragment.